Zou, L., Susko, E., Field, C. and Roger, A.J. (2012).
Fitting Nonstationary General-time-reversible Models to Obtain Edge-lengths and Frequencies for the Barry-Hartigan Model.
Systematic Biology.61:927--940.
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source code as well as the required
lapack library source code (version 3.3.1) if it is not available on your system.
This software is provided by Liwen Zou , who should be contacted if you have any questions. Software last updated: April 26, 2012.

Susko, E. (2003). Confidence Regions and Hypothesis Tests for Topologies Using Generalized
Least Squares. Molecular Biology and Evolution.20(6):862--868.
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The software for this paper has been substantially revised so that covariance matrix estimates are better conditioned and more model options are available. Please see the software for Susko (2011) "Improved Least Squares Topology Testing and Estimation." listed above.